Shunt switch for electric light circuits



(No Model.)

2 Sheets-Sheet 1. E. THOMSON.

SAFETY SELF CLOSING SHUNT SWITCH FOR ELECTRIC LIGHT CIRCUITS ml min Si v Patented Apr. 3, 1883.

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B. THOMSON.

SAFETY SELF CLOSING SHUNT SWITCH FOR ELECTRIC IGHT CIRCUITS. No. 275,290. Patented jpr. 3,1883.

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N. PETERS. Phata-Lillmgraphm, wasmn mnv 0 c "UNITED STATES PATENT OFFICE.

ELIHU THOMSON, OF NEW BRITAIN, CONNECTICUT, ASSIGNOR TO THE AMERICAN ELECTRIC COMPANY, OF SAME PLACE.

SAFETY SELF-CLOSING SHUNT-SWlTCH FOR ELECTRIC-LIGHT CIRCUITS.

SPECIFICATION forming part of Letters Patent No, 275,293, dated April 8, 1883,

Application filed January 22, 1883. (No model.)

To all whom it may concern Be it known that I, ELIHU THOMSON, a citizen of the United States, and a resident of New Britain, in the county of Hartford and State of Connecticut, have invented certain new and useful Improvements in Safety Self- Closing ShnntSwitches for Electric Lamps, Motors, &c., of which the following is a specification.

Myinvention relates to electric shuntingswitches used in combination with electric lamps, electric motors, or other electric apparatus placed in circuit with a dynamo-machine or other generator or source of electricity, and operated by hand or at will for the purpose of cutting the electric lamp or other apparatus out of circuit.

The object of my invention is to provide a means whereby, in case that portion of the general circuit containing the lamp or other apparatus is interrupted and defective, the shunting-switch will be immediately and automatically reclosed, if under such conditions it be operated to break the shunt and throw the lamp into circuit.

In the practical operation ot'electric-lighting systems it very often happens that when the shunting-switch of a lamp is opened to throw the lamp into circuit an arc is formed across the switch-contact, owing to an interruption or defect in the lamp-circuit or that portion of the general circuit shunted by the switch. If the switch remain open, the parts will bet'used and destroyed and the whole circuit upon which the lamp or lamps are placed will be interrupted.

My invention overcomes this difficulty by providing a means for automatically reclosing the shunt in case the lamp-circuit is interrupted so as to cause an arc to be formed across the switch-contacts, and the switch cannot under such circumstances be turned and the shunt be left open by the attendant or person who attempts to throw the lamp or other apparatus into circuit.

My invention consists in combining with a shunting-switch for an electric lamp or other apparatus suitable mechanism, mechanical or magnetic, which will tend to close the shunt and recomplete the circuit around. the lamp or other apparatus, and in controlling the open ation of said restoring device by the agency of the electric current, which flows or is forced into or through the shunt in case an attempt is made to open said shunt while the portion of the general circuit containing the electric lamp or otherapparatus is broken or defective.

My invention consists,also, of a special combination in which suitable devices are made to act upon the shuntingswitch itself, so as to bring the contacts of said switch itself together in case the current continues to flow in the shunt when the switch is opened, the operation of such device upon the switch being controlled or effected by the agency of the currentflowing in the shunt,as will be hereinafter described.

Myinventionconsists,also,ofcertainspecific combinations of devices for carrying out the invention, that will be indicated in the claims. In carrying my invention into practice I propose to depend upon the thermahthe magnetic, or any other elfects ot' the current which may flow into or through the shunt when the switch is turned to break the shunt, and the lamp-circuitor that portion of the general circuit containing the lamp or other apparatus is at the same time broken or defective. I may therefore employ an electromagnetic coil or helix connected in or to the shunt-circuit; or I may depend upon the thermal effects of the electric current which at the time flows into the shunt. In the latter case I may use an expausible conductor, through which the electric current flows, or I may depend upon the Q thermal effects of the are which forms across the shunt-contacts when the shunt is broken, the heat of the are acting upon a fusible material-such as an alloy-a combustible cord,or upon a thermostatic device consisting of a compound bar or other thermo-mechanical agent.

Some of the devices which maybe employed for thus utilizing the current flowing in the shunt for eti'ecting or bringing about the closing of the shunt or an automatic restoration of the switch itself to a closed position will be hereinafter described.

The device for acting upon the switch itself or the auxiliary shunt-closer and throwing it to a closed position (the operation of which device is controlled or eit' ected by the agency of the current flowing in the shunt when the ICK switch is opened) may be either mechanical or magnetic-that is, I may use a spring, weight, or other power, or I may employ magnetic attraction produced preferably by the current itself flowing in the shunt. The latter is the simpler way, as the current flowingin the shunt to control or effect the closing of the switch may then be the agency or power by which the switch is actually thrown.

In the case of a spring or similar device, suitable detaining mechanism is employed for holding the switch or circuit-closing device open when the conditions are such that the switch may remain open without endangering itself or the continuity of the general circuit, and said detaining mechanism is controlled by the effects (thermal or magnetic) of theelectric current flowing in the shunt in such away that the detaining mechanism shall hold the switch open when no current flows on opening the switch, but shall release or be out of engagement with the switch it' under such conditions a current flow.

Some of the various arrangements of the elements employed in carrying out my inventions that may be used are shown in the ac con'ipanying drawings, and are illustrated as applied to an electric lamp, although they may he also used with electric motors or other ap paratus placed in circuit with a generator or source of electricity so as to be operated thereby.

Figure l is aside view of a switch that contains a magnet For automatically throwing the same into closed position. Fig. 2 illustrates a switch containing a spring-actuator and detaining mechanism therefor, controlled by an electro-magnct in the shunt-circuit. Figs. 3 and 4t show the switch of Fig. 2 in the two positions of closed and open. Fig. 5 is a modification in which the thermal effects of the are formed between the switch-contacts are employed instead of a magnet. Fig. 6 is another modificatiomin which an expansible conductor is employed in place of the magnet 01 Fig. 2 and the compound bar of Fig. 5. Fig. 7 shows a modified arrangement of the controlling electro-magnet. Fig. 8 illustrates the manner in which the heating effects of the are formed at the switch-contacts may cause a release of the circuit-closing device for the shunt by melting a fusible material. Fig. 9 is a modification in which an auxiliary circuit-closing device is used for closing the shunt when the are forms, instead of the shunting-switch itself, as in Fig. 8. Fig. 10 shows how a combustible or fusible non-conducting film may be used for normally holding the contacts of an auxiliary circuit-closer apart, and may be melted or destroyed when an are forms between the shunting-switch contacts, so as to allow the shunt to be closed. Fig. 11 shows how a detaining fusible cord is combined with an auxiliary shuntcircuit closer and the shunting-switch.

In Fig. 1, A indicates an electric lamp or equivalent apparatus in the general circuit 9 ot' a generator or source of electricity, while L indicates the lever of the shunting switch, which is of any desirable shape or form, is operated by a button or knob, 12, and is con nected to the general circuit 9 9, so that when it closes circuit at S B in the usual. way it will cut the lamp out of circuit by completing a shunt or short circuit around it. M indicates an eleetro-magnet which is in the shunt or short circuit, one end of its coil beingconnected to the pivot of the switch-lever L, while the other end is connected directly to the general circuit, as indicated. The electro-magnet 111 is mounted on the switch-lever L, while its armature M is fixed in any suitable manner, and acts to draw the electro-magnet and switch lever toward the contact B whenever current tlowsthroughthecoilsotM. Suitablestopslimit the movement of the switch-lever. \Vhen the shunting-switch is opened, it no adequate passage exist for the current at A, the current, passing or arcing over the switch-contacts at B S and circulating through the coils M, will draw the switch-lever over and restore the contact at B S the moment the hand of the person 0peratingitis withdrawn. Thecontinuityof the general circuit will thus be automatically preserved and the destruction of the switch pre vented. Thedeviceisespeciallyvaluablewhen the switch-contacts are out of sight, so that an are, it formed, cannot be seen, so as to give warning of the detective circuit in A, or when the apparatus is in the hands of ignorant persons.

In Fig. 2 a spring, Z, is used for drawing the lever L over to close the shunt, in place of the armature M The electro-magnet M acts to hold a detaining device t'orthe lever out of engagement therewith when current flows through the coils of the electromagnet. N is the armature-lever ot' the electromagnet M, which lever carries or controls a catch, 0, that tends to engage with a notch or shoulder at C on the switch-lever L when the armaturelever N is retracted, and when so engaged detains the lever L in the position shown in Fig. -1- and prevents the spring Z from drawing the lever over so as to close the shunt-circuit at B S. A depending chain or cord, (1, may be provided for the purpose of disengaging the catch when it is desired to shunt the lamp. When the lamp is shunted the parts are in the position shown in Fig. 3 and the switch is held over by spring Z. When the lever is turned to start the lamp and current still flow across the switch-surface B S and through coils M, owing to an inadequate path in A, the spring Z will act to restore the switch imme diately when the hand is removed, because the electro-magnet M will hold the detaining devices out of engagement. it, however, the circuit through A is complete, the current will cease to flow through the shunt the moment that B and S are separated, so that the catch 0 will engage with G and hold the lever L back until the armature-lever is drawn down by hand or other means independent of the clectromagnet M.

In Fig.5 a compound bar of dissimilar metals-such as is used for thermostats,thermometers, and other thermo-mechanical devicestakes the place of the electro-magnet M, and is arranged in suitable proximity to the shunting-switch contacts B S, so as to become heated by any are that may form between said contacts. B indicatesthe compound bar, which is fixed at one end byany suitable means, and at its free end is connected by a link, i, with a lever carrying the catch 0. The parts are so set and arranged that the elasticity of the bar B when not heated tends to draw up the catch 0 and thus detain the lever L when the latter breaks the shunt without forming the are. If, however, through the breaking of the circuitin A, an arc form at B S, the bar is heated and lowers the catch (3, so as to carry it away from a point where it will engage the lever L, thus allowing the spring, when the hand is removed, to immediately restore the lever to the position in which it will close the shunt.

In Fig.6 an expansibleconducting-wire, D in the shunt-circuit serves to control the detaining device and the switch. hen the cur rent flows through the shunt the wire I) is lengthened and the catch 0 is lowered away from its engaging position. It, however, the shunt is broken at B S, when the lever L is turned the wire shortens and draws up the catch, so that itwill engage with and hold the lever back when the hand is removed. A spring, D gives the requisite elasticity to the support for C, so that it can he disengaged by pulling on the chain or cord 0*.

In Fig. 7 the electro-magnet M is not in the direct shunt-circuit with the switclrcontacts proper; but an accessory plate, S is provided, near which the upper end of L moves. The electro-inagnet M is placed in a circuit, 15, from 9 to S When the switch contact S is opened with an arc the arc is transferred to the nearer plate, S thus putting the electromagnet M into circuit, so that it will attract the armature LT and reclose the switch. This arrangement of the plates S S, and L might be used with the other mechanical or electrical devices herein described.

In Fig.8 the thermal effects ot' any are torming between the shunting-switch contacts are utilized for releasing a shunt-circuit closer. The switch -plate L is made in two parts, hinged together at B, and the hinge is soldered with some readily-fusible material or alloy. Thejoint or hinge B is sufficiently near the points B S to be heated quickly by any are that may form. So-long as the soldered or cemented joint at B remains intact the switch may be operated in the ordinary way, and will retain the position shown in full lines when thrown to such position by hand or otherwise. It',however,in opening the switch an are forms at S, the heat soi'tens or melts the solder or cementat B, and the spring Z is then free to act so as to close the contact atB S.

In Fig. 9 thet'usible material which controls the action of the device which serves to close the shunt, it a current continues to flow in it after the switch is turned, is applied in a little different way. In this case, as in Figs. 10 and 11,211 auxiliary shunt-circuit closer is employed; but the principle of operation is the same as when the shunting-switch proper is controlled. \V indicates a strained elastic wire, mounted on lever I1 and in electric connection therewith. A pin or stud, I), of some readily-fusible material, holds the spring in the posit-ion shown by the full line. This pin is fused whenever an arc is formed between the switch -surt'aees S B, thus releasing the wire or spring W, which by its own elasticity is brought into contact with B, or a stud, It, thereon, thus closing the shunt.

In Fig. 10 a conducting-plate, H is attached to contact B, as shown, and carries a sheet 01 tilm of an insulating combustible or fusible material,F-such as paper or waX-which serves to normally keep a spring, G, out of electrical connection with the plate. Spring G is connected, as shown, so that when it makes contact with H the lamp or other device at A is shunted. It an arc form between L and B, the sheet of paper or other material is carbonized, softened, or melted, so that the spring G can penetrate to the plate H and thus close and preserve the shunt, and also prevent destruction ol the contacts S, L, and I) by the are.

In Fig. it a string or wire, K, of fusible or combustible material, is employed as the means For controlling the operation of the device, which closes the shunt when the opening of the switch does not produce a break of the shunt-circuit. t is the spring circuit-closer, which is held out of contact with stop H by the t'usible connection K, but which is so conuected, as shown, as to close a shunt when it comes into contact with H The cord or wire K is arranged in suitable proximity to the switch contacts S B, so that if an arc form on opening the switch, the cord or wire will be burned or t'uscd, and will thus allow the circuit-closer to act and close the shunt-circuit.

Many other devices for carrying out my in vention will readily suggest themselves to those skilled in the art, and I do not therefore limit myself to any special forms of circuitclosers or of electrical, thermal, or other devices that may be arranged to be affected by the current circulating in the shunt when the shunting-switch is opened, and to control or cause the operation of the shunting switch proper or of an auxiliary shunting-switch.

I make no specific claim herein to the specific combinations of devices in which the thermal effects of the current circulating in the shunt after the shunting-switch is opened are utilized for controlling or causing the operation of the shunting or auxiliary switch, so as to cause an immediate reclosing of the shunt, as this forms the subject of another of my applications for patent.

-What I claim as my invention is Iit'.

1. The combination, with an electric lamp or other apparatus, as described, in circuit with a generator or source of electricity, of a shunting-switch, circuit-closing devices for closing the shunt, actuated or controlled by the effects of the electric current which may liow in the shunt after the opening of the shunting-switch, substantially as and for the purpose described.

2. The combination, with an electric lamp or other apparatus, as described, of a shunting-switch, devices for closing said shunt, and means for actuating or allowing the operation of said devices so as to complete a shunt-circuit upon the passage of a current across the contacts of the shunting-switch on opening the same.

3. The combination, with an electric lamp or other apparatus, as described, ot'a shuntingswitch, devices for automatically bringing the contacts of said switch together in case the current continues to liow in the shunt after the switch is opened, the operation of such devices upon the switch being controlled or effected by the agency of the current flowing, substantially as and for the purpose described.

4. The combination, with an electric lamp or other apparatus, as described, of a shuntingswitch, devices for restoring said switch to a closed position when it is opened, and means torbringing said devicesinto operation to close said switch upon the passage of a current across the switch-contacts at the time of opening the switch.

5. The combination, with an electric lamp or other electric apparatus, as described, of a shunting switch, means for restoring said switch to a shunting position, and a helix in or connected to the shunt-circuit, so as to be energized when a current passes throughsaid shunt, and controlling the operation of the restoring mechanism, so as to prevent said switch from remaining in opened position while cur- 1ent is forced across the contacts by reason of the rupture or imperfection of that portion of the general circuit containing the lamp.

6. The combination, with an electric lamp or other electric apparatus, of a shunt-switch, a device, magnetic or mechanical, for closing said switch automatically, and an electric coil in the shunt circuit controlling the action of the closing device and causing or allowing the operation ol'said device to immediately reclose the switch whenever on opening the same the main or principal circuit is interrupted or defective, so as to cause a current to pass the switch-contacts as they are separated.

7. The combination, with an electric lamp or other apparatus, as described, ot' a shuntingswitch, a spring or equivalent motor tending to close the switch, a detaining device for holding the said switch open, and means for controlling the action of said detaining device in the manner described, so as to release the switch whenever a current flows across the switchcontacts on opening the switch.

8. The combination, with aneleotriclamp or other apparatus in circuit with a suitable source of electricity, ot' a shunting-switch, a spring or equivalent device tending to close the switch, a catch for engaging with the switch and holding it open when said switch is thrown back to break the shunt, and suitable means, as described, t'or holding the catch away from the point where it will engage with the switch, energized or rendered operative for the purpose by the current which flows through the shunt across the switch-contacts when the switch is turned to break the shunt.

9. The combination, with an electric lamp or other device in circuit with a suitable source 0t electricity, of a shuntingswitch for said device, a spring or its equivalent tending to close the switch, a catch for engaging with the switch when it is thrown to break the shunt, and an electroma-guet connected to the shuntcircuit, so as to be energized when a current passes the separated contacts of the switch, and when so energized holding the catch away from its engaging position.

Signed at New Britain, in the county of Hartford and State of Connecticut, this 17th day of January, A. I). 1883.

lGL'I H U THUM SON. YVitnesses:

E. WILBUR Bron, W. 0. WAKEFIELD. 

